The examination of cancer cells collected from effusions and ascites is an important step to identify or determine the progress of cancer by pathologists or in preparation of performing analytical techniques by cancer scientists. However this examination is complicated due to the presence of many noncancerous cells, including mesothelial, macrophage, and lymphocyte cells. Standard preparation techniques such as centrifugation can be utilized to increase the density of total cells in the sample, but further purification of the collected sample to highly enrich the cancer cells is troublesome and expensive, typically requiring laborious processing and expensive labeling reagents such as antibodies. As such, enriching cancer cells from ascites is rarely performed in the clinic and infrequently in the research laboratory. The objective of this research proposal is to test a label free microfluidic cell sorting technology that utilizes differences in cell stiffness and cell sizeto enrich cancer cells from noncancerous cells present in ascites fluid. The technology utilizes the observed fact that the cancer cells frequently undergo biophysical and morphological changes to be distinct from other noncancerous cell types. The technology consists of microchannels with periodic constrictions that are designed to direct soft cells along a different path than stif cells. We will examine how variations in channel geometry and other system parameters can be harnessed to provoke cancer cell segregation through inherent biophysical differences. A high throughput and label-free method to purify cancer cells from noncancerous cells will greatly benefit the accuracy and efficiency of both cancer science and clinical diagnoses. Successful completion of this project will create a new enrichment method to facilitate the detection of very low levels of diseased cells in complex fluids or to enhance the purity of cancer cell subpopulations within heterogeneous mixtures, including effusions and ascites fluid.